(a) Field of the Invention
The present invention relates to a thin film transistor (“TFT”) array panel and a liquid crystal display (“LCD”) device, and more particularly, to a TFT array panel and a LCD device capable of improving luminance by enhancing an efficiency of light used from, for example, a backlight unit.
(b) Description of the Related Art
The LCD is one of the most widely used flat panel displays, and includes two display panels on which field generating electrodes, such as pixel electrodes and a common electrode, are formed, and a liquid crystal layer interposed between the two display panels.
A voltage is applied to the field generating electrodes formed on the two display panels to generate an electric field at the liquid crystal layer to thereby control an alignment of liquid crystal molecules within the liquid crystal layer and control polarization of an incident light to display desired images.
In terms of a light source, LCD types can be divided into a backlit LCD that displays images by using a backlight positioned at a rear surface of a liquid crystal cell, and a reflective LCD that displays images by using external light. In addition, the LCD types also includes a transflective LCD that combines structures of the backlit LCD and the reflective LCD. The transflective LCD is operated in a backlit mode (transmission mode) in which images are displayed by using an internal light source of the LCD in a room or in a dark area where there is no external light, and is also operated in a reflective mode in which images are displayed by reflecting an external light in an environment with a high intensity of illumination.
Of the LCD types, the backlit LCD and the transflective LCD, both of which display images by using the backlight, are commonly used because of their advantage of having a high display luminance.
However, the backlit LCD and the transflective LCD have problems in that approximately 50% of incident light from the backlight is absorbed by a polarizer attached on a lower portion of the LCD and only the remaining 50% or so of the light is used to display an image, thereby degrading the light efficiency and the display luminance.